American Indian (AI) youth consistently report higher use of drugs than other populations in the United States. Further, AI youth are as likely, if not more so, to experience serious consequences from drug use. However much remains unknown: The extant literature is largely restricted to AI youth and, generally, little attention is paid to cultural differences. A more comprehensive description of the negative consequences of drug use is needed. Finally, incorporation of availability, access, and acceptability of health services into the understanding of health disparities is warranted. This proposal responds to RFA DA-01-008 with a plan to make significant progress in depicting and understanding these disparities. Data from the recently completed American Indian Service Utilization, Psychiatric Epidemiology, and Risk/Protective Factors Project (AI-SUPERPFP) provide an opportunity to better understand the drug-related health disparities between 2 of the largest tribal populations. The specific aims are 1) To develop models of the biopsychosocial factors important to understanding health disparities in drug use and its adverse consequences. 2) To depict the disparities in the use of drugs (including tobacco) between 2 AI populations and, further, to investigate the degree to which ethnic differences in biopsychosocial factors may account for these disparities. 3) To depict the disparities in the behavioral, social, medical, and mental health consequences of drug use and to investigate the degree to which differences in biopsychosocial factors and drug use explain these disparities. 4) To describe the disparities in utilization of health services and to investigate the relationships of health services, biopsychosocial factors, drug use, and adverse consequences. 5) To place these findings in a national context with the use of judicious comparisons to the National Comorbidity Survey (NCS) 14-19 and the National Household Survey of Drug Abuse (NHSDA). The proposed analyses of AI-SUPERPFP--the first large-scale, community-based alcohol, drug and mental health (ADM) epidemiologic study of AIs promises to provide insights drug-related health disparities in a manner never before possible: first with a thorough investigation of such disparities across two of the largest, but culturally distinct, tribal groups; and later with targeted comparisons of these findings with national data from two comparable efforts with national samples. Furthermore, the Division of American Indian and Alaska Native Programs (DAIANP) provides a unique multidisciplinary environment (including staff from psychology, psychiatry, internal medicine, demography, anthropology, and public health) in which to conduct this work, thus promising to inform disparities research more generally.